Salt – simple mineral or life saver?

As a nation of weather watchers, winter in particular can strike fear into the stoutest hearts as dropping temperatures leave us wondering about commuting to and from wherever we are and wherever we need to be. Whether by air, rail or road, freezing temperatures have been known to bring the UK to a grinding halt. In particular the condition of our roads can create traffic chaos and regrettably, accidents with their associated heartache, with just a few millimetres of snow and ice as the winter of 2009 proved.

Technology?

So in this age of science and technology, where we can predict all manner of things, including the weather, how do we deal with icy road conditions? In exactly the same way that we’ve done for the last 50 plus years – we grit the roads with rock salt, most of which comes from Cheshire and a mine that has operated since 1844.

Historically speaking

The salt deposits used to grit our roads were discovered by prospectors searching for coal. Formed during the Triassic era (220 million years ago) when the Cheshire plain would have been under a shallow warm sea, as the water evaporated salt crystals formed and were tinged pink with the help of sands blown in from eastern deserts – other geological influences mean its colour varies from clear to pink and dark brown. If you doubt the desert connection think of the Sandstone so common in Cheshire.

Above ground there is little trace of the roads and chambers and hive of industry that keeps the countries roads clear so you might be forgiven for being unaware of but walk along certain parts of the River Weaver and the keen eyed amongst you will spot not only sea grasses growing in abundance but also the Sea Aster, all due to the level of salt in the soil.

Underground Road System

The Winsford mine has grown over a large underground area around 5km East to West and 3km North to South with 150 miles of roadways with an incredibly dry atmosphere and a constant temperature of 14oC. It can produce up to 8,000 tonnes of rock salt a day and at this time of year is on standby to meet the demand the Highways Agency and the weather put on it and accounts for 50% of the grit spread on UK roads. Towns around Winsford bear names ending in ‘wich’ relating to the brine springs e.g. Northwich, Middlewich and Nantwich and all have a long history of salt extraction, even in Roman times.

Great Use of Space

Although some of the space hewn into chambers from the salt face is a graveyard for old and disused machinery that can’t be brought to the surface – neither practical nor necessary it does have other uses. The dry environment with its constant temperature surprisingly is also the perfect storage facility for delicate manuscripts and books, with the excavated voids holding archive materials for a number of organisations.

And in future?

The geology creates an incredibly stable environment and there is more than 918 million cubic feet of space available. It is growing all the time as the huge 160 ton machines continue to carve out tunnels 200 metres below ground with the available space expected to treble in size over the next 70 years.